\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{patterns}
\begin{document}
\footnotesize
  \begin{tikzpicture}[>=stealth]
    \begin{scope}
      \draw[thick](0,0)rectangle(1,0.2)(1.2,0.2)rectangle(1.4,-0.7);
      \draw[thin](1.0,0.25)--++(0,0.3)(1.2,0.25)--++(0,0.3);
      \draw[thin,->](0.7,0.45)--(1.0,0.45)node[midway,above]{$\Delta$};
      \draw[thin,->](1.4,0.45)--(1.2,0.45);
    \end{scope}
    \begin{scope}[xshift=1.8cm]
      \draw[thick](0,0)rectangle(1,0.2)(0.4,-0.15)rectangle(0.6,-0.7);
      \draw[thin](1.05,0)--(1.35,0)(0.65,-0.15)--(1.35,-0.15);
      \draw[thin,->](1.3,-0.45)--(1.3,-0.15)node[midway,sloped,above]{$\Delta$};
      \draw[thin,->](1.3,0.2)--(1.3,0);
    \end{scope}
    \begin{scope}[xshift=-1.8cm,yshift=-0.2cm]
      \draw[thick](1,0)--(0,0)--(0,0.1)--++(0.2,0.2)--(1,0.3);
      \draw[thin](1,-0.1)--++(0,0.15)--++(30:0.1)--++(150:0.2)--++(30:0.1)--++(0,0.15);
      \draw[thick](-1.2,0.1)--(-0.2,0.1)--(-0.2,0.2)--++(-0.2,0.2)--(-1.2,0.4);
      \draw[thin](-1.2,0)--++(0,0.15)--++(30:0.1)--++(150:0.2)--++(30:0.1)--++(0,0.15);
      \draw[thin](1.05,0.3)--++(0.5,0)(1.05,0.0)--++(0.5,0);
      \draw[thin,<->](1.5,0)--++(0,0.3)node[midway,sloped,above]{$t$};
      \draw[thin](-0.2,0)--++(0,-0.5)(0,-0.1)--++(0,-0.4);
      \draw[thin,->](-0.4,-0.4)--++(0.2,0)node[midway,above]{$b$};
      \draw[thin,->](0.2,-0.4)--++(-0.2,0);
      \draw[thin](-0.3,0.4)--(0.7,0.4);
      \draw[thin,<-](0.6,0.4)--(0.6,0.6)node[midway,sloped,above]{$\delta$};
      \draw[thin,->](0.6,0.1)--++(0,0.2);
    \end{scope}
  \end{tikzpicture}
\end{document}